## Individual gas constants for some gases (J/kg x K)

Gas
Air
Argon
Helium
Hydrogen
Nitrogen
Oxygen
Water vapour
R - 12
R - 22
Ri
287
208
2079
4116
297
260
461
68.7
96.1

If many calculations are made for the same gas, it is often easier to use the individual gas constant Ri

$p \times V = \nu \times Ri \times T$